<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    div{
        width: 600px;
        height: 200px;
        background: -webkit-linear-gradient(top left,red,blue);
    }
</style>
<body>
<div></div>
</body>
</html>